<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .tudou {
            position: relative;
            width: 448px;
            height: 252px;
            margin: 0 auto;
            background-color: #19e055;
        }

        .mask {
            /* 使遮罩 mask 这个盒子在 tudou  这个盒子里面 */
            position: absolute;
            top: 0px;
            left: 0px;
            width: 100%;
            height: 100%;
            /* 中间那个小按钮背景图片的设置 */
            background: rgba(0, 0, 0, 0.4);
            background-image: url(images/arr.png);
            background-repeat: no-repeat;
            background-position: center;
            display: none;
        }


        /* 当鼠标经过土豆这个盒子时就让mask这个盒子显示出来 */
        .tudou:hover .mask {
            display: block;
        }
    </style>
</head>

<body>
    <div class="tudou">
        <img src="images/tudou.jpg" alt="">
        <div class="mask"></div>
    </div>
</body>

</html>